Rudeboy

This brings up topics I'd hope we'd get into in this thread: sound deadening materials in an SPL setup and matching the treatment to the goals. Let's start with extreme SPL. Introducing high pressures into a vehicle exceeds the manufacturer's design. Something has to give to relieve the pressure. The exact path will be the one with the least resistance. Could be an air leak, could be sheet metal displacement or deformation or most impressively to some, the glass may break. Because of rules and habit, the traditional reaction has been to start layering on vibration damper. This might help or it might hurt - we've all seen posts describing small gains or small losses. There's no predictable outcome. How can this be? I can think of two possible mechanisms that could increase SPL: the vibration damper seals air leaks or it adds a small amount of reinforcement to the sheet metal. It's pretty easy to see that both outcomes are inappropriate applications for vibration damper. It's easier to see how vibration damper can lower scores since that's basically what it is designed to do. Vibration dampers work by converting vibration - which can become measurable sound, into heat - which can't. Even if a vibration damper application increases overall pressures, it does so in spite of converting at least some of the available energy into an unusable form. To predictably improve a vehicle's capacity to hold pressure, seal leaks and brace panels in a way that doesn't bring an offsetting conversion of energy to the party. Now let's suppose you don't care about numbers on a meter, you like your music loud and you just want to stop your roof from flapping around. The basic solution is still the same: mechanically reinforce it. Vibration damper is an inefficient solution to gross movement. If you use a bracing method that subdivides the roof - metal or wooden "beams" for example, you'll gain something else in the process, you will have divided the roof into smaller panels. Each smaller panel will have a higher resonant frequency that the entire roof did. Vibration dampers are more effective in this range. You'll be able to use less if you are trying to quiet things down and if it's a combination SPL competition vehicle and daily driver, you'll lose less energy to heat.

That's interesting. Is there any space between the inner sheet metal and the headliner?

Are you putting your hand on the roof or the headliner? Where are the rattles coming from?

Sorry I missed this. The really important concept to grasp about any rattle is that it is always two or more hard objects moving and making intermittent contact. Seems obvious but keeping that in mind helps when trying to track them and that's really what you need to do to kill them. Vibration dampers, like CLD Tiles have been promoted as a cure for rattles. This approach may or may not work. It's always the indirect way to solve the problem. If it works, it works because you have successfully reduced the energy available to move the objects that are making contact. A more surefire solution is to identify the objects and either stop them from moving or put something soft between them to prevent contact. This can be a simple as tightening a bolt or screw, adding a blob of RTV silicone or lining one of the surfaces with foam. This all boils down to detective work. What is rattling? The best way to find out is to play music or test tones that cause it and then start feeling around with your hands. Does pressing on the trim panel stop it? Probably the trim panel rattling against the inner skin. A layer of CCF between the two will solve the problem. Can you narrow it down to two pieces of the trim panel? Maybe lock them down with some silicone. No luck? Try the latch handle and lock nob - could be a cable or actuator rod.

Premature post. Cascade and Second Skin sell very good products. All of the liquids and pastes are vibration dampers. As I mentioned, you don't need a lot of supplemental vibration damper on the floor. That means you'd need to use these products as barriers. They will be less effective in this application since they are tightly bonded to the sheet metal. More importantly, a barrier's performance depends on how much it increases the mass of what is already there - you need to double mass to gain an audible improvement. Adding 1 lb/ft² to sheet metal that starts around 1/2 lb/ft² does that. Any idea how thick the application of a liquid product would have to be to get to 1 lb/ft²? I don't remember, but it think it is 6mm or so, roughly 1/4" inch. I can't even guess how many cans of an aerosol it would take to coat the entire underside of even a small car to that thickness. You would need to cover the entire underside since sound will bend around a more difficult barrier to follow an easier path. Here's something else to consider when you contemplate a treatment that needs to be permanently bonded to a vehicle's sheet metal. What happens if you need body work? I've been wondering about this for some time and is why I encourage anyone who isn't building a one purpose or disposable vehicle to make as few permanent changes as they can to get the results you want. I've been sharing a building with a body shop and now have an informed answer - it can make a minor repair a major repair that insurance won't cover. PDR won't work and panels that could be repaired will have to replaced because of the time required to remove layers of vibration damper. Since there's no performance advantage, why do it?

This shouldn't be an SDS product specific thread. I'll be posting some test results for CLD Tiles on the SDS site in the next few weeks that should show that the adhesive used has been tested more thoroughly than any other product on the market. Going through the catalog, product by product, would be beyond the intended scope of this thread but I will try to get more data on the SDS site. I'm confident enough that every product I sell belongs in the top tier of this category that I happily send free sample kits to anyone who requests them (in the US). Nothing like hands on to evaluate quality.

Danny, Some of that depends on how you define "outside noise". If you mean noise that doesn't come directly from your vehicle or its interaction with the environment, doors would be first since they let in most traffic noise. Doors make a good first project. They can be done without disturbing the rest of the vehicle. I know from personal experience that you can drive a car for days without trim panels. On warm days you can drive without glass Noise rejection treatments involve installing a barrier. If you hang this layer from the inner skin and have door mounted speakers, you'll also be isolating the front and rear wave coming from the cone, improving speaker performance. An interesting thing happens when you start by treating one area. In a noisy car, you are sitting in a swirl of sound coming from every direction. This makes it difficult to localize the sources. Treat just the doors and you are likely to be able hear engine, exhaust and tire/wheel noise better than you could before. It's not louder, just easier to localize and identify. That leaves noises generated by the vehicle - engine, exhaust and its interaction with the environment - tire/wheel and wind, maybe rain too. Engine, exhaust and tire/wheel noise are complicated. The firewall and floor are where they penetrate, but not exactly as we tend to think. Engine and exhaust noise do hit the passenger compartment in a direct line, but they also reflect off the pavement, meaning they even enter through areas from which you can't draw a straight line back to the source. Tire noise is especially interesting. Most of us think that most of it comes in through the wheel wells. That's led to all sorts of exterior treatments that are supposed to avoid the complication of getting to the interior surface of the floor. It seldom makes an audible difference. The important point is that tire noise starts at the contact patch with the pavement and radiates up in every direction from there. A lot of the sound that would otherwise pass through the wheel well is blocked by the tire and wheel. The reality is that tire noise enters through most of the floor. Interestingly and despite years of tradition pointing in exactly the opposite direction, you generally don't need much supplemental vibration damper on the floor of a vehicle, especially if you don't plan to remove and replace the factory application. The floor is almost always braced and reinforced in a variety of ways that make it much less susceptible to resonance than other areas like the doors, roof and quarter panels. Add the bolted down seats and the weight of a human being or more and you are most of the way there. A barrier layer is always going to yield the biggest improvement. Spare tire wells are another area that have been traditionally over treated to the extreme. The usual approach is to remove the spare, tap the sheet metal and marvel at the flimsy construction and extreme resonance. Many wheel wells WILL benefit from some supplemental treatment. The confusion results from the fact that the spare itself is part of the manufacturer's NVH treatment. With the spare in place, the well has completely different characteristics. The roof is interesting. Glass will always be the weak link in any noise attenuation program. This isn't as big a problem as we might fear because most of the noise we are concerned about strikes the vehicle below the glass line. What this means in terms of treatments is that a barrier isn't going to help much unless you are frequently exposed to noise sources directly overhead. I had one customer who spent a lot of his day driving around an airfield. For most of us it isn't a problem. Resonance can be a major problem for the roof, especially since it is such a large panel, right above your head. This resonance can be excited by a wide variety of sources. My rule is to tap on the roof from outside the vehicle. If it rings, treat it. If not, it's probably not worth the effort.

I dropped the ball. Not even sure how. It's happened a few times that an incoming message gets marked read before I reply or the system hangs while I have a message open. Sorry about that. I responded to the original message so Phil and I should be able to pick this up. It's usually safe to assume that if I don't respond in a day or two, something is up. I'm a little concerned about this: "these xcons are doing some work on my car." There are two things I can think of that this might mean. The first is that the subs are exciting panel resonance that needs to be controlled. Vibration damper may be a good solution for this. The second is that this is an SPL setup and the XCONs are tearing the vehicle apart. In that case, traditional sound deadening techniques are probably a poor fit. Using vibration damper to structurally reinforce sheet metal is much less effective than other approaches and is likely to have a negative impact on scores since the mechanism of vibration damping - converting vibration (which can become sound) into heat (which can't) is taking things in the wrong direction. In any case, I screwed up and it shouldn't have happened.

It's been my pleasure. Stay safe.

Late model Mazdas have unusual doors, similar to Minis and some VWs. The inner skin has a large plastic insert in the center to which all of the moving parts are attached. This structure has advantages and disadvantages. Any effective treatment is going to require removing the plastic piece, so learning how to do that is a very good starting point. Exactly what you do from there will depend on what you want to accomplish. My standard door treatment is vibration damper on the inner and outer skins. You have sheet metal around the edges of the inner skin that will benefit from some vibration damper. The plastic part is highly reinforced and convoluted, so there isn't much to be gained from applying vibration damper to the plastic part. Adding vibration damper to the sheet metal will make the doors sound much more substantial when opened and closed. It will also control resonance in the sheet metal and that will help a little with the rattle. My preferred door treatment is to apply vibration damper and then add a barrier between the inner skin and trim panel. There are many advantages to this approach but it isn't possible in your case because of the way the inner skin and trim panel mate. The removable plastic insert does make the outer skin easy to get to. If blocking noise from outside the car is a concern, hanging the barrier on the outer skin is really your only option. To get to the trim panel rattles, you'll want to get as much closed cell foam between the inner skin and trim panel as will fit and not interfere with the doors' operation.

I went back and forth on mounting amps to my box. At the end of the day this is exactly what I said. I bet when you said it you put "box" between "built" and "really"

You'd ideally want isolation mounts. I thin McMaster-Carr has a good selection. I know it's generally considered a bad thing to do, but how much is the wall of a properly built really going to vibrate? Shouldn't be much.

It really depends on what you are trying to accomplish. If you're purely going for SPL, you have to be careful with how you use vibration damper. The simple fact is that vibration dampers turn vibrations, that can become sound, into heat, that can't. For SPL, you want the vehicle to contain pressure. Picture a balloon and a beer bottle. You can create a lot more internal pressure forcing air into the beer bottle than the balloon. The balloon will expand to accommodate the air. Both will explode at some point, but the beer bottle will resist a lot more pressure before it does. Now cover the balloon with Band-Aids. It'll resist a little more pressure than before, but still no where near the beer bottle. You want an SPL vehicle to be a beer bottle. You get there by bracing the panels that would otherwise distort in response to the pressure you are exposing them to. It really doesn't matter how thick the foil on a CLD is - it is going to be a poor stiffener for steel. It's also going to be converting vibration to heat. You can have it both ways, sort of. If you want to contain pressure but also want to eliminate resonance at lower volumes - when you care what the music sounds like, brace the panels in a way that divides each into several smaller panels. This is going to limit the amplitude of the resonance and each sub-panel will have a higher resonant frequency than the undivided panel did. A bit of CLD on each sub-panel will control that efficiently. Since the amplitude is limited by the bracing, less energy will be converted into an unmeasurable heat.

It's really important when looking at a problem like this to figure out what is going on. The quick answer is always "put some deadener (vibration damper) on it" but that may not really be what you need. Vibration damper will control panel resonance. That vibration can eventually loosen panels and lead to rattles but remember - rattles are always two or more hard objects making intermittent contact. Adding vibration damper may help and it may help prevent the conditions that led to the rattling, or not. We care about panel resonance because it can energize rattles, but more because it selectively reinforces the sound we hear at the natural frequency of the resonating panel. This only matters when you are looking for accurate reproduction. We also want to control panel resonance because it is a mechanism for transmitting noise into the vehicle from the outside. All of this means that sound deadener (vibration damper) has an important role to play when we care about quality musical reproduction and a quiet vehicle. It sounds to me like you were happy with things at first, beat the hell out of the vehicle and now it's starting to rattle. If what you want is to get back to the way things used to be, vibration damper isn't going to be the best answer. What we're really talking about in this case is accelerated wear. All of the clips and fasteners that used to be nice and snug have been moved around enough that they are wearing out. I'm really tempted to make an analogy to a a woman here, but will resist the urge. There are basically two approaches you can take to this problem. You can go through the vehicle and replace the clips and fasteners so that they are tight again or you can put something between the objects making contact to stop them from doing so. The best material for this is closed cell foam. Line the backs of the trim panels. Soft will be hitting hard and it won't make any noise. This will also take up some of the slack that has been created. If you care about resonance, apply vibration damper to the sheet metal while the panels are off. If not, you're good. This is really the inevitable result of adding more pressure to the system than it was designed to handle. Big dude, little chick kind of problem (couldn't resist )

If the trunk is sealed off, noise coming through the trunk shouldn't be a problem. If the trunk won't be seeing any sound from the subs, it won't sound bad outside the car. No reason to do anything else to the trunk that I can see.

Why not one of these? More than enough power bridged to run through your crossover or 4 channels if you want to run active.

Not for blowing the speakers, but for sounding terrible, definitely. It's a pretty common scenario: Upgrade HU and the stock speakers sound much better. Figured that was a win and upgrade the speakers and it sounds much worse. I'd be willing to be that the OP's car sounded better with the upgraded HU and stock speakers than it does now. He is asking the HU's internal amp to do something they can't - power his new speakers. He turns the volume way up to compensate and the speakers happily reproduced a distorted signal. Treating the doors isn't going to help that situation enough to be the first or only thing he should do. Gotta match the speakers with the power they need.

It sounds like drastically under powering your speakers is the biggest problem right now. A distorted signal isn't going to be cleaned up by door treatment. I'd get an amp first.

Pictures would help. I'm definitely a fan of fiberglass. This thread shows two different ways to seal doors and goes through a full door treatment.

2 hours later, inner skin as good as it's going to get - About 10 hours after that - One door, floor and roof and I'm done

That's what she said

I'd be hating life slightly more if I gone over the access holes with vibration damper - just slightly.

Oh noes ...

I wouldn't have started if I'd known how difficult it was going to be. Now that I'm halfway through, I'm going to finish out of spite. Putting aside the whole topic of how much vibration damper coverage you need to be effective, something that I never thought of is the impact covering everything with even one layer has on future body work. I share space with a body shop. The guys there have taken an interest in this project. Aside from Aaron, they're also pretty much the only people who don't look at me like I'm crazy for doing it They've told me about cars that have come in with dings in the doors that could otherwise have been fixed with a $100 PDR. Because the owner had covered the outer skin in Dynamat (their example), PDR was impossible. Repairs that require welding are impossible. The time required to remove the material before working on the sheet metal is not covered by insurance. Simple and inexpensive repairs become expensive and complicated repairs require replacing the entire panel. They agreed that removing 25% coverage wouldn't phase them at all. Half the time they find some small patches of LCD inside doors that was installed at the factory. Since there's no benefit to be gained by full coverage - let alone what I did, and it presents potential problems in the future, there's no reason to do it. I wish I'd know 5 years ago what I know now.